I'm currently with this, now.
Greninja w Mystic Water
Water/Dark
Ability: Torrent
Nature: Timid
EVs: 252 SAtk / 252 Spd / 4 HP
Moves: Surf, Ice Beam, Dark Pulse, Extrasensory
Sylveon w Pixie Plate
Fairy
Ability: Cute Charm
Nature: Modest
EVs: 252 HP / 252 SAtk / 4 Spd
Moves: Draining Kiss, Moon Blast, Psyshock, Dig
Porygon-Z w Life Orb
Normal
Ability: Adaptability
Nature: Modest
EVs: 252 Spd / 252 SAtk / 4HP
Moves: Nasty Plot, Hyper Beam, Tri Attack, Hidden Power
Heliolisk w Choice Specs
Electric/Normal
Ability: Solar Power
Nature: Timid
EVs: 252 SAtk / 252 Spd / 4 HP
Moves: Grass Knot, Hidden Power, Volt Switch, Thunderbolt
Anybody can help me filling the other two slots cause I can't decide much about it. Please rate my team so I could improve it a bit. ;)
You need to specify your Pokemon's Hidden Power types.
Greninja should always use its Protean ability:
-Hydro Pump/Surf
-Ice Beam/Dark Pulse
-Extrasensory/Dark Pulse
-U-turn/Hidden Power (Fire/Grass)/Grass Knot
Nature: Naive/Timid
EVs: 4 Atk/252 SAtk/252 Spe
Item: Life Orb/Expert Belt
Ability: Protean
or
-Spikes
-Hydro Pump/Surf
-Ice Beam
-U-turn/Extrasensory
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb/Focus Sash
Draining Kiss is too weak; not even its healing effect can save it from being unusable. Dig also works off of Sylveon's terrible Attack. While Pixilate + Hyper Voice is preferred for Sylveon, Moonblast + Cute Charm is an acceptable alternative if you can't transfer from Poke Bank:
-Wish
-Protect
-Hyper Voice
-Heal Bell/Calm Mind
Nature: Bold
EVs: 252 HP/244 Def/12 Spe
Item: Leftovers
Ability: Pixilate
or
-Hyper Voice
-Shadow Ball
-Psyshock
-Hidden Power (Fire)/Baton Pass
Nature: Modest
EVs: 244 HP/252 SAtk/12 Spe
Item: Choice Specs
Ability: Pixilate
Hyper Beam is a big no-no move on Porygon-Z. It leaves it a sitting duck the turn after it's used:
-Nasty Plot
-Tri Attack
-Dark Pulse
-Hidden Power (Fighting)
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb
Ability: Adaptability
Other Adaptability users are Crawdaunt and Mega Lucario (note that the latter is an Uber in simulators):
Crawdaunt:
-Crab Hammer
-Knock Off
-Aqua Jet
-Crunch/Swords Dance
Nature: Adamant
EVs: 4 HP/252 Atk/252 Spe
Item: Choice Band/Life Orb/Mystic Water
Ability: Adaptability
Mega Lucario:
-Swords Dance
-Close Combat
-Extreme Speed
-Crunch/Ice Punch/Bullet Punch/Shadow Claw
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Lucarionite
or
-Nasty Plot
-Aura Sphere
-Flash Cannon
-Dark Pulse/Shadow Ball/Vacuum Wave
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Lucarionite
Ability: Inner Focus/Steadfast
I think that Heliolisk is somewhat subpar. It doesn't have a way to hit Dragons effectively outside of Hidden Power. Wash Rotom is better, IMO, as it can counter Talonflame:
or
-Volt Switch
-Hydro Pump
-Hidden Power (Ice)/Thunderbolt
-Will-o-Wisp
Nature: Modest
EVs: 228 HP/60 SAtk/220 Spe
Item: Leftovers
or
-Volt Switch
-Hydro Pump
-Thunderbolt/Hidden Power (Ice)
-Trick
Nature: Timid/Modest
EVs: 4 HP/252 SAtk/252 Spe
Item: Choice Scarf
A hazard setter would be ideal for this team, like Ferrothorn or Skarmory:
Ferrothorn:
-Spikes/Stealth Rock
-Leech Seed
-Gyro Ball/Thunder Wave
-Power Whip/Protect
Nature: Relaxed
EVs: 252 HP/48 Def/208 SDef
Item: Leftovers/Shed Shell/Rocky Helmet
Ability: Iron Barbs
Skarmory:
-Roost
-Whirlwind
-Stealth Rock/Spikes/Brave Bird
-Defog/Brave Bird
Nature: Bold/Impish
EVs: 252 HP/252 Def/4 SDef or 252 HP/16 Def/240 SDef
Item: Leftovers/Rocky Helmet
Ability: Sturdy
or
-Spikes
-Roost
-Whirlwind
-Taunt/Brave Bird
Nature: Bold/Impish
EVs: 252 HP/184 Def/72 Spe
Item: Leftovers
Ability: Sturdy
Can't think of anything for the 6th slot, atm.